1. Field of the Invention
The present invention relates to X-ray imaging device.
2. Related Background Art
X-ray imaging device using charge-coupled device (abbreviated to “CCD” hereinafter) is an imaging device having superior energy resolution and position resolution. X-ray imaging device using back-illuminated CCD excels in low energy X-ray detection efficiency because electrodes for charge transfer do not shield X-ray to be detected. This causes the X-ray imaging device using back-illuminated CCD to detect X-ray within a predetermined energy range (for example, from 0.1 to 20 keV (called “soft X-ray” hereinafter)).
Since CCD is made from silicon (Si), absorption of X-ray with a higher energy range (for example, from 20 to 100 keV (called “hard X-ray”)) than the predetermined energy range is extremely low. Consequently, hard X-ray is not detected at CCD and passes through the CCD. Therefore, in order to detect hard X-ray, it is inevitable to use X-ray imaging device provided with scintillator to convert X-ray into visible light, so that the detection of any X-ray within a wide energy range (that is, soft X-ray and hard X-ray) with one imaging device was not possible.
The radiation detector with a plurality of PIN photodiodes laminated via insulators is known, which can detect X-ray with different energy ranges using each PIN photodiode.